Linux: Watching large directories is still pegging CPU

[bpasero]

Describe the bug
I am giving [email protected] a try to see if watching large directories still keeps the CPU busy or not. My simple test shows no difference to previous versions so I wonder if there is a new option that is needed.

Versions (please complete the following information):

• Chokidar version: 3.0.0
• Node version: 10.15.1
• OS version: Linux p520 4.15.0-50-generic #54-Ubuntu SMP Mon May 6 18:46:08 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

To Reproduce

const chokidar = require("chokidar");

const watcher = chokidar.watch('/', {
    ignoreInitial: true,
    ignorePermissionErrors: true
});

Expected behavior
By default, I would expect to not see high CPU spikes when watching. I think the default options should optimise for low hits on CPU.

Additional context
High CPU from watching large folders is an issue VSCode users are reporting very often (microsoft/vscode#3998).

PS: this is the first time I see how many processes chokidar produces when looked at via htop, any clues?

[paulmillr]

Yeah, the fact it creates many processes is not normal. I haven’t saw this behavior while testing the lib. Can you try watching NOT root directory? There are a few files that may break something. Perhaps watch user directory.

[bpasero]

@paulmillr pretty much the same when watching just home:

Btw I see those flood of processes even appearing when watching a folder that does not exist...

[paulmillr]

that’s not normal at all. I wonder what’s the difference here.

[bpasero]

Almost looks like node was using some kind of clustering. I have never seen this before.

[paulmillr]

Could you see whether there's any difference after upgrading to node 12.x?

[paulmillr]

Also, try chokidar@master — we've changed a few things...

[bpasero]

@paulmillr same result with node.js 12.3.1 and master: high CPU and multiple node processes.

On macOS I see high CPU but just a single node process.

[paulmillr]

3.2 should fix this.

[vilicvane]

@paulmillr Does this issue affect version ^2?

[paulmillr]

No, you should upgrade